t could be their outdoor culture. A mountainous and temperate state, Colorado is well-known for hiking, skiing, and the like. In 2009, 82.3 percent of Coloradans said they'd been physically active within the last month, according to a survey from the Centers for Disease Control and Prevention. The median for all states was 76.2 percent. Colorado is also tied with Oregon for 49th place in physical inactivity among adults. State health department officials suggest that Colorado's hiking and fitness culture could draw trim and sporty types to move there, in which case lanky carpetbaggers might be helping to keep obesity rates down.

Demographically, the state had a lot going for it. We know that poverty and obesity are strongly correlated, and that people with more education are less likely to be obese. In 2008, 13.2 percent of Americans were living below the poverty line. In Colorado, that number was 11.4 percent, or 18th-best in the nation. According to the Lumina Foundation for Education, in that same year 37.9 percent of Americans between the ages of 25 and 64 held a college degree or higher, but in Colorado that number was 45.3 percent. (Only Connecticut, Massachusetts, and New Hampshire—all of which are thinner than average—rank higher in college degrees.)